1. Field of the Invention
The invention relates to a device for sealing between two assembly parts that are movable relative to one another and in particular, to a device for sealing on the shut-off elements of flue gas fittings.
2. Description of the Related Art
German Patent No. DE 38 15 402 A1 discloses a device for sealing the contact zone between a movable shut-off element of a pipeline and a stationary seat, which uses an elastic seal in the form of an elongated spring-steel strip as the sealing element and is positioned in the sealing area. Outside of the arched sealing zone, in the longitudinal direction of the sealing element, the spring-steel strip has two bends. The two longitudinal edge areas of the spring-steel strip point to the same side and are placed one atop the other, as clamping edges, and can be attached to the movable shut-off element or to the stationary seal seat by means of a clamping device (e.g., a screw connection). This seal has proved to be very effective, particularly when the relative movement which occurs between the spring-steel strip and the matching seal seat during the closing process is roughly vertical relative to the arched sealing zone. In cases when the relative movement during closing is more tangential relative to the arched sealing zone, situations of extreme stress for the spring-steel seal sometimes develop, which can result in the spring-steel strip being lifted up from the supporting surface and, in consequence, in breakage of the spring-steel strip.
In order to avoid negative consequences of this type, it is known from WO 95/02136 to provide a supporting profile in the interior of the sealing element. This supporting profile, which serves as a hold-down device for the spring-steel strip, rests on the supporting surface of the spring-steel strip near the bend located farthest from the clamping point and prevents the strip from lifting up when the strip experiences tangentially directed forces. The hold-down device can be designed, for example, as a generally V-shaped profile, and it is secured between the clamping edges of the spring-steel strip by means of the clamping device. Because extraordinarily corrosive conditions frequently occur in flue gas fittings, the hold-down device, like the spring-steel strip, must be made of high-alloy material, making it quite expensive. It is also disadvantageous that when a large-area flue gas damper equipped with one of the known sealing elements is opened, the break-away torque resulting from the hold-down device can be undesirably high.